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Reticulum II

In this article, we will explore and analyze the topic of Reticulum II in depth. Throughout history, Reticulum II has played a fundamental role in numerous aspects of human life, from its impact on society to its influence on culture and technology. Through this article, we will seek to better understand the importance of Reticulum II and its relevance in today's world. We will examine its origins, its evolution over time and its impact on the modern world. In addition, we will explore different perspectives and opinions on Reticulum II, offering a complete and enriching vision of the topic.

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Reticulum II
Observation data (J2000 epoch)
ConstellationReticulum
Right ascension03h 35m 42.14s[1]
Declination−54° 2′ 57.1″[1]
Distance103 kly (31.6 kpc)[2]
Apparent magnitude (V)17.4[1]
Characteristics
Apparent size (V)3.37′ × 3.64′[1]
Notable featuresEnriched in r-process elements
Other designations
Reticulum II, Reticulum 2[1]

Reticulum II (or Reticulum 2) is a dwarf galaxy in the Local Group. Reticulum II was discovered in 2015 by analysing images from the Dark Energy Survey. It is a satellite of the Magellanic Clouds and was probably captured relatively recently.[3] Like other dwarf spheroidal galaxies, its stellar population is old: the galaxy was quenched before 11.5 billion years ago.[3]

Reticulum II is elongated, having a major/minor axis ratio of 0.6. The size is given by a half-light radius of 15 parsecs (pc). This is too large for it to be a globular cluster. The absolute magnitude (MV) of the galaxy is −2.7. The distance from Earth is about 30 kpc.[2] The galaxy contains some blue horizontal branch stars. Other features visible are a main sequence, and a main sequence turn off, and a red giant branch.[1][4] It has an unusual enhancement of r-process elements, meaning that gold and europium are enriched in the brightest stars in the galaxy.[5] About 72% of its stars are enriched in r-process elements.[2] The implication of the unusual enrichment in elements heavier than zinc, is that the r-process is very rare, and only happened once in this galaxy, possibly by the collision of two neutron stars.[6]

Gamma rays mostly with energies between 2 and 10 GeV have been detected by the Fermi satellite.[7] The radiation from Reticulum II is more significant than that of other dwarf galaxy emissions.[8] However this finding has been contested.[9]

References

  1. ^ a b c d e f Sergey E. Koposov; Vasily Belokurov; Gabriel Torrealba; N. Wyn Evans (10 March 2015). "Beasts of the Southern Wild. Discovery of a large number of Ultra Faint satellites in the vicinity of the Magellanic Clouds". The Astrophysical Journal. 805 (2): 130. arXiv:1503.02079. Bibcode:2015ApJ...805..130K. doi:10.1088/0004-637X/805/2/130. S2CID 118267222.
  2. ^ a b c Simon, Joshua D.; et al. (2023). "Timing the r-process Enrichment of the Ultra-faint Dwarf Galaxy Reticulum II". The Astrophysical Journal. 944 (1): 43. arXiv:2212.00810. Bibcode:2023ApJ...944...43S. doi:10.3847/1538-4357/aca9d1. S2CID 254221028.
  3. ^ a b Sacchi, Elena; Richstein, Hannah; Kallivayalil, Nitya; Van Der Marel, Roeland; Libralato, Mattia; Zivick, Paul; Besla, Gurtina; Brown, Thomas M.; Choi, Yumi; Deason, Alis; Fritz, Tobias; Geha, Marla; Guhathakurta, Puragra; Jeon, Myoungwon; Kirby, Evan; Majewski, Steven R.; Patel, Ekta; Simon, Joshua D.; Tony Sohn, Sangmo; Tollerud, Erik; Wetzel, Andrew (2021). "Star Formation Histories of Ultra-faint Dwarf Galaxies: Environmental Differences between Magellanic and Non-Magellanic Satellites?". The Astrophysical Journal Letters. 920 (1): L19. arXiv:2108.04271. Bibcode:2021ApJ...920L..19S. doi:10.3847/2041-8213/ac2aa3. S2CID 236965965.
  4. ^ DES Collaboration (10 March 2015). "Eight New Milky Way Companions Discovered in First-Year Dark Energy Survey Data". The Astrophysical Journal. 807 (1): 50. arXiv:1503.02584. Bibcode:2015ApJ...807...50B. doi:10.1088/0004-637X/807/1/50. S2CID 12011753.
  5. ^ Ji, Alex (22 March 2016). "The Origin of the Cosmos' Heaviest Elements". Phys.org. Retrieved 24 March 2016.
  6. ^ Ji, Alexander P.; Frebel, Anna; Chiti, Anirudh; Simon, Joshua D. (21 March 2016). "R-process enrichment from a single event in an ancient dwarf galaxy". Nature. 531 (7596): 610–613. arXiv:1512.01558. Bibcode:2016Natur.531..610J. doi:10.1038/nature17425. PMID 27001693. S2CID 205248401.
  7. ^ Hooper, Dan; Linden, Tim (3 September 2015). "On The gamma-ray emission from Reticulum II and other dwarf galaxies". Journal of Cosmology and Astroparticle Physics. 2015 (9): 016. arXiv:1503.06209. Bibcode:2015JCAP...09..016H. doi:10.1088/1475-7516/2015/09/016. S2CID 118482641.
  8. ^ Geringer-Sameth, Alex; Walker, Matthew G.; Koushiappas, Savvas M.; Koposov, Sergey E.; Belokurov, Vasily; Torrealba, Gabriel; Evans, N. Wyn (17 August 2015). "Indication of Gamma-Ray Emission from the Newly Discovered Dwarf Galaxy Reticulum II". Physical Review Letters. 115 (8) 081101. arXiv:1503.02320. Bibcode:2015PhRvL.115h1101G. doi:10.1103/PhysRevLett.115.081101. PMID 26340176. S2CID 16494335.
  9. ^ Overbye, Dennis (10 March 2015). "Gamma Rays May Be Clue on Dark Matter". The New York Times. Retrieved 20 October 2016.
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